The goal of this project is to determine the extent to which symmetric transcription occurs in HeLa cells. The fraction of heterogeneous nuclear RNA (hnRNA) that is symmetrically transcribed will be determined by self-annealing hnRNA and assaying for duplex formation. The duplex RNA fraction will then be hybridized to isolate single-copy DNA to determine its sequence complexity. To determine whether mRNA-coding regions themselves are symmetrically transcribed, mRNA will be hybridized directly to hnRNA and the formation of RNA duplexes will be assayed. If it is shown that symmetric transcription is a major aspect of the RNA synthetic process, its cause will be investigated. To determine if HeLa cell transcription is unrestricted, hnRNA will be probed for RNA sequences, such as globin gene transcripts, that are not expected to be expressed. A library of cloned human DNA fragments in the bacteriophage lambda Charon 4A vector will then be screened for symmetrically-transcribed DNA sequences. Cloned DNA fragments will be isolated and characterized using restriction endonuclease mapping procedures to determine the relationship between symmetrically-transcribed and mRNA-coding regions. This analysis will be carried out with the intention of determining whether the HeLa cell genome has genes arranged in close proximity on both DNA strands, like that of adenovirus.